Neural crest cells (NC cells) are essential to establishing the vertebrate body plan, contributing many critical cell types. Understanding the molecular mechanisms that control the formation and development of these cells is of high importance to understanding congenital defects, and for regenerative medicine. Moreover, several of the proteins upon which this proposal centers have clear and established links to the formation of tumor initiating cells (aka Cancer Stem Cells) and metastasis. By further elucidating the mechanisms by which these proteins regulate the normal development of NC and pluripotent blastula/ES cells, we will gain further insight into their role in NC derived tumors, ad in stemness, malignant transformation and invasive cell behavior more generally. We have previously identified factors underlying NC cell potency, including Myc and Id3. The work proposed here is potentially paradigm shifting as it presents and tests a novel hypothesis for the origins of NC cells and their relationship to pluripotent blastula/inner cell mass cells. We propose that a regulatory network supporting pluripotency in the blastula ectoderm is at least partially retained in select cells through gastrulation, and by neurula stage these cells are located at the neural plate border, and become NC cells by virtue of their retained potency. We also dissect regulatory targets of key potency factors, and test the hypothesis that Snail proteins, key regulators of NC, ES and cancer stem cells, are context dependent factors that both activate and repress key target genes. The proposed aims will significantly advance our understanding of an important cell type, and provide a new framework with which to understand their origins and stem cell attributes. This work has high potential to drive novel approaches to stem cell bases therapies, as well as cancer diagnostics/ therapeutics